The present invention relates generally to a proximity detector system for a device having a self-propelled chassis. More particularly, the invention relates to an ultrasonic detector system for a medical diagnostic device which automatically stops the device when an obstacle is detected to be in close proximity to the front of the device.
Various types of equipment are made mobile by mounting the equipment on a self-propelled chassis. Mobility is particularly significant for medical diagnostic equipment, such as an X-ray device and a scintillation camera device for obtaining diagnostic images of a patient. In many cases, the patient requires intensive care or critical care and cannot be moved, so the diagnostic device must be transported to the patient. The device may be required to be operated virtually anywhere in the hospital. The device must maneuver along extremely long corridors, around life support systems and around monitoring systems or traction devices. The device must also move in and out of elevators, through doorways, up wheelchair ramps, over carpeting and tile, and across small open thresholds.
A problem is presented by the mobilization of scintillation camera equipment which is used to detect gamma ray photons emitted from a body in which a radioisotope has been infused to produce a diagnostic image of the patient. Scintillations occur where photons are absorbed by crystalline material. The scintillations are received by a detector head which contains scintillation crystals, photomultiplier tubes and lead shielding. A typical system is based on the camera of Anger, as disclosed in U.S. Pat. No. 3,011,057, and is herein incorporated by reference. The detector head, along with the suspension arm, weighs approximately 300 pounds. The suspension system and column for the detector head add more weight along with the very high density of electronic instrumentation used to analyze and display the diagnostic images of the patient. The substantial size and weight of the diagnostic equipment requires a similarly substantial chassis and mobility drive system to transport the equipment. The combined equipment and mobility chassis weighs over 2,000 pounds and presents the problem of safely maneuvering, steering and braking the device while it is being moved and then stabilizing the device once it is in position.
A particular problem associated with the mobile diagnostic device is that of providing limited visibility to the operator. The device is normally controlled with steering handles located at the rear by an operator walking behind the device. The substantial size of the equipment permits the operator to view only along the left or right side of the device. The visibility of the operator is significantly limited to the front and opposite side of the device. The 2000 pound mass traveling at 3 feet per second could present a hazard to any unseen person or obstacle in the path of the device. In addition to detecting an obstacle in the path of the device, it is important to instantly respond and apply the brakes to avoid colliding with close proximity obstacles. This problem is particularly acute while passing through intersections and while turning corners within the hospital.
Accordingly, one object of the present invention is to provide a diagnostic device which can be safely operated at relatively high speeds through corridors of a hospital.
Another object is to provide a diagnostic device which can be safely controlled by an operator walking behind the device.
Still a further object of the present invention is to provide a diagnostic device which automatically stops when an obstacle is in the immediate path of the device.